A popular notion of preserving privacy is \(k\) -anonymity [1]}; for synthetic data, this is the requirement that for any \(y \in \lbrace \mathcal {A}(x_1),\dots , \mathcal {A}(x_n)\rbrace \) , the preimage \(\mathcal {A}^{-1}(y)\)  has cardinality at least \(k\) . In words, the true data is transformed into synthetic data in such a manner that the information of each person in the dataset cannot be distinguished from that of at least \(k-1\)  other individuals in the dataset.
